Vibronic structure in the low lying Rydberg states of hexafluorobenzene and 1,3,5-trifluorobenzene detected by two-photon spectroscopy

(2+1) Resonance-enhanced multiphoton ionization (REMPI) spectra were recorded for hexafluorobenzene (HFBz) and 1,3,5-trifluorobenzene (TRFBz) using UV laser light. Vibronic structure of the Rydberg series converging to the first ionization threshold are resolved. While only one Rydberg series is observed for HFBz (region 67 500–70 820 cm−1), two of them are detected for TRFBz (region 66 000–69 100 cm−1). The resolved vibronic structures are assigned with the aid of theoretical predictions.